My GPU - an Intel 4600 integrated GPU in a 2014 laptop - kicked up to about 95% utilization while playing with the site. I suspect I was getting fewer details than you - mine was not silky smooth but still perfectly usable, at what I'd estimate to be about 20 FPS.
That your powerful GPU was putting in some effort while my poky GPU [edit: and my 2018 low-end Android phone, admittedly at ~4FPS] are still able to render the scene at all indicates to me that they put in some impressive effort to make the graphics scale for different configurations!
That your powerful GPU was putting in some effort while my poky GPU [edit: and my 2018 low-end Android phone, admittedly at ~4FPS] are still able to render the scene at all indicates to me that they put in some impressive effort to make the graphics scale for different configurations!